Depending on who you asked, the notion of a roadway across the Straits of Mackinac was either prohibitively expensive or architecturally inconceivable: An enormous undertaking that, in the first half of a century marked by two World Wars and the Great Depression, seemed an impossible feat.

But that didn't stop some Michiganders from dreaming.

A floating tunnel was suggested, as was a series of island-hopping causeways from Cheboygan to St. Ignace. In the mid-1930's, though, a study by the newly formed Mackinac Straits Bridge Authority had determined that a bridge would indeed be the state's best bet for linking its two peninsulas. By then, the ferry service established at the Straits had proven wildly popular -- so much so that traffic congestion in Mackinaw City had become staggering, especially for weekends during the summer tourism and fall hunting seasons. It was clear that a road between the peninsulas was warranted.

But deciding to try building a bridge -- one that eventually would become known to Michiganders as "the Bridge," with an almost audible capital B -- was only the start of the epic endeavor that would give rise to our state's mightiest icon.

While the ferries kept chugging away at the Straits in the 1930's, Bridge Authority officials crunched numbers and talked logistics. Twice before 1936, the organization asked the Federal Emergency Administration of Public Works for assistance in funding a bridge at the Straits, but twice these requests were denied. Undaunted, the Bridge Authority pressed forward, selecting a specific route for the proposed roadway and studying everything from the region's geology to its water currents.

In 1940 an architectural catastrophe in Washington created an unnerving moment of doubt for Michigan's bridge believers, when the Tacoma Narrows Bridge -- nicknamed "Galloping Gertie" for its propensity to sway in gusty conditions -- twisted so violently in 40 m.p.h. winds that it broke apart and collapsed into Puget Sound. It had been a suspension bridge -- just like the proposed bridge at the Straits.

"The Straits of Mackinac are a very windy location," says Bob Sweeney, current executive secretary of the Mackinac Bridge Authority. "Galloping Gertie collapsed in a wind storm of about 42 m.p.h. -- in the Straits that [kind of weather] happens on a monthly basis, if not more often than that."

On top of that spectacular disaster, a number of engineers claimed that the fractured limestone at the bottom of the Straits couldn't handle the weight of a bridge. But David B. Steinman -- the structural engineer and architect eventually chosen to design the Mackinac Bridge -- would prove them all wrong.

Steinman studied the Galloping Gertie debacle and applied its lessons to his bridge design for Mackinac, adding counterweight and an open-truss section to combat oscillation in windy weather. He also employed the idea of massive footings to reduce the pressure on the limestone bedrock that had made naysayers out of other engineers.

By this time, the Bridge Authority had devised a plan to finance the bridge through bonds totaling nearly $100,000,000, allowing contracts to be awarded for the marine construction and steel companies that would make this project happen.

With both the finances and a design finally locked down, the largest bridge-construction fleet ever assembled descended on the Straits. The vision that so many had been dreamed about for decades officially began its transformation to reality with weekend ceremonies in early May, 1954.

Construction at the Straits took place over three years, employing more than 10,000 workers: Some 3,500 workers at the site itself, plus more than 7,000 more at quarries, steel mills and other machine shops. Five men died during its construction -- a fact that's as remarkable as it is tragic, given the potential dangers of the labor and the conditions often present at the Straits. (For proof of how formidable the workers were, check out this video of the Bridge's construction, where you can watch tradesmen tightening bolts, sans safety harnesses, in blowing snow.)